This ends up being a pretty easy objective for students to master. It becomes kind of silly to ask them over and over again to multiply three numbers to find the volume. I ended up adding, on the fly, a few more volume problems where students had to find an unknown dimension given the volume and two other dimensions. May some problems using algebraic expressions would be a good side.

Example:

The volume of a rectangular prism is 240 cubic units. The length is x -5 units, the width is 12 units and the height is 3 units. What is the length of the prism?

This would help this "additional" standard help support the "major cluster" - expressions and equations.

More Problems Like 5

Adjustments to Practice: More Problems Like 5

Explore Volume of Rectangular Prisms

Explore Volume of Rectangular Prisms

Unit 6: Geometry
Lesson 31 of 37

Objective: SWBAT discover the formula for the volume of a prism through problem solving

I will collect the unifix cubes before this section. Now we are moving to the pictorial activity. Students will be given a few minutes to answer the questions on the page. As students are working, I will walk around to assess student work. Problems 1 & 2 are essential for students understanding the generic formula for the volume of prisms, so I will initially focus my attention there.

Question 4 is an opportunity for students to develop a viable argument (MP3). The bullet points are provided to help them construct their arguments. Any number of answers may be appropriate, but they must be well constructed answers. For example: “I see that the number of cubes in each layer is equal to the product of the length and width of the prism.” A well formed argument will use language precisely as well (MP6)! Question C1 and C2 are so that students can see that rotations do not affect volume or surface area. We will have a share out of findings before moving on to the next section.

Resources

Now I would like my students to work through some problems independently. There are only 5 problems, so I expect everybody to make it to the extension questions. Notice these are just a variation on the warmup acitivity. The only difference here is that I only want unique combinations (not permutations). I will most likely not allow any calculator use as the problems are pretty straight forward and questions 4-5 provide a good review of decimal multiplication and division.

Extension question B is a review of surface area. It also allows students to develop MP1 and MP3.

Resources (1)

Resources

The exit ticket has 2 simple application problems and a slightly more difficult 3 problem, where the volume is given but one dimension is missing. It is very important that students show their work or explain their solution for problem #3. Some may write an equation; others may use arithmetic only. Either way is fine as long as they can justify the answer.